1. Field of the Invention
The present invention relates to an image forming apparatus for continuously feeding cut paper.
2. Description of the Related Art
Generally, various image forming apparatuses, such as copiers, printers and facsimiles, employ paper as an image medium. The user of these apparatuses has to pay attention to a residual amount of paper and, if the paper is used up, replenish new paper promptly. On the other hand, a data output apparatus, such as a printer and a facsimile, unlike a copier and so on, is often not attended by an attendant. In order to initially prevent a possible inoperative state of the printer, facsimile, and so on, in particular, due to the absence of paper stored therein, it is necessary to, when a residual amount of paper is lowered below a predetermined level, inform the "absence of paper" state of the user and replenish paper.
In the existing printer and facsimile equipment using continuous paper, such as roll paper, a mark is coated as an "absence of paper" warning mark on the rear side of the continuous paper over a predetermined length range at the end portion of the continuous paper and new continuous paper is replenished in place of the "nearly used up" paper.
In recent times, a page printer using those cut paper sheets obtained by cutting plain continuous paper to a given length through the use of the electrophotography technique has extensively been accepted in view of its operability, its image keeping property and other excellent features. Further, the so-called plain paper facsimile equipment (FAX) using the electrophotography technique at the printer section emerges on the market. The page printer and plain paper FAX are also demanded for personal use as a compact unit to meet the personal OA equipments, such as computers and word processors.
In the page printer and plain paper FAX as set out above, many cut paper sheets are stored in a paper supply section and continuously fed to an image forming section by paper feeding means, such as paper supply rolls. In this case, it is not possible, unlike the continuous paper, to initially coat an "absence of paper" warning mark on the cut paper. This is because those cut paper sheets with such an "absence of paper" warning mark, if being so used, have to be so stored as to be fed at a subsequent phase of a paper feeding sequence and hence the advantages of using the cut paper sheets are impaired. Further, such a marked paper sheet as being also found in the continuous paper sheet is often unsightly for use as a formal document and undesirable for a storage purpose. For a relatively large page printer and plain paper FAX, use is made of a method for detecting a residual amount of paper sheets by, for example, a light sensor and blinking an "absence of paper" warning lamp in accordance with the detection signal. In this case, the user sometimes overlooks the blinked warning lamp. Instead of blinking the warning lamp, a warning mark display information may be sent to the image forming section, and then a warning mark is given on cut paper being sent. However, this method, like the above-described method, is undesirable for a storage purpose and makes the image forming control complex.